My sister and I shared a bed room for most of our early years until I graduated from high school. When we were real young mom used to bath us together. We slept thgether in a double bed. We also slept in the nude.
Eventually we started playing with each other touching, feeling, inspecting. I would get hard-on's which she thought was great. Mom knew but didn't mind. She said not to do it when others were around.
Mom knew because we asked questions, which she always answered, showed or explained. Sis grabbed my penis in the bath and said, watch mom, and proceded to give me a hard-on. Mom laughed and said that's what happens when a guy gets stimulated. With the hot water and mom there I really got hard. Mom rinsed us and sent us to bed, where we played a bit.
As we grew older the playing turned into masturbation sessions. My sister would put the thumb-knuck on her clit and push down hard and move it around, and I learned to jack-off.
Mom came in the room once and caught me jackin. I was in the 6th grade I think. She smiled and sat on the bed and told me that was a normal thing for guys to do.S he took my penis in her hand and it got hard again. She said, my you are getting big. She ask if it felt good when I did it, and asked if stuff squrted out of it. I told her no, but it felt good. It was shortly after this we moved to another house. That's another confession for later.